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    <div class="refentry" id="textureGrad">
      <div class="titlepage"/>
      <div class="refnamediv">
        <h2>Name</h2>
        <p>textureGrad — perform a texture lookup with explicit gradients</p>
      </div>
      <div class="refsynopsisdiv">
        <h2>Declaration</h2>
        <div class="funcsynopsis">
          <table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
            <tr>
              <td>
                <code class="funcdef">gvec4 <strong class="fsfunc">textureGrad</strong>(</code>
              </td>
              <td>gsampler2D <var class="pdparam">sampler</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec2 <var class="pdparam">P</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec2 <var class="pdparam">dPdx</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec2 <var class="pdparam">dPdy</var><code>)</code>;</td>
            </tr>
          </table>
          <div class="funcprototype-spacer"> </div>
          <table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
            <tr>
              <td>
                <code class="funcdef">gvec4 <strong class="fsfunc">textureGrad</strong>(</code>
              </td>
              <td>gsampler3D <var class="pdparam">sampler</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec3 <var class="pdparam">P</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec3 <var class="pdparam">dPdx</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec3 <var class="pdparam">dPdy</var><code>)</code>;</td>
            </tr>
          </table>
          <div class="funcprototype-spacer"> </div>
          <table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
            <tr>
              <td>
                <code class="funcdef">gvec4 <strong class="fsfunc">textureGrad</strong>(</code>
              </td>
              <td>gsamplerCube <var class="pdparam">sampler</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec3 <var class="pdparam">P</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec3 <var class="pdparam">dPdx</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec3 <var class="pdparam">dPdy</var><code>)</code>;</td>
            </tr>
          </table>
          <div class="funcprototype-spacer"> </div>
          <table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
            <tr>
              <td>
                <code class="funcdef">float <strong class="fsfunc">textureGrad</strong>(</code>
              </td>
              <td>sampler2DShadow <var class="pdparam">sampler</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec3 <var class="pdparam">P</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec2 <var class="pdparam">dPdx</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec2 <var class="pdparam">dPdy</var><code>)</code>;</td>
            </tr>
          </table>
          <div class="funcprototype-spacer"> </div>
          <table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
            <tr>
              <td>
                <code class="funcdef">float <strong class="fsfunc">textureGrad</strong>(</code>
              </td>
              <td>samplerCubeShadow <var class="pdparam">sampler</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec4 <var class="pdparam">P</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec3 <var class="pdparam">dPdx</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec3 <var class="pdparam">dPdy</var><code>)</code>;</td>
            </tr>
          </table>
          <div class="funcprototype-spacer"> </div>
          <table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
            <tr>
              <td>
                <code class="funcdef">gvec4 <strong class="fsfunc">textureGrad</strong>(</code>
              </td>
              <td>gsampler2DArray <var class="pdparam">sampler</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec3 <var class="pdparam">P</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec2 <var class="pdparam">dPdx</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec2 <var class="pdparam">dPdy</var><code>)</code>;</td>
            </tr>
          </table>
          <div class="funcprototype-spacer"> </div>
          <table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
            <tr>
              <td>
                <code class="funcdef">float <strong class="fsfunc">textureGrad</strong>(</code>
              </td>
              <td>gsampler2DArrayShadow <var class="pdparam">sampler</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec4 <var class="pdparam">P</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec2 <var class="pdparam">dPdx</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>vec2 <var class="pdparam">dPdy</var><code>)</code>;</td>
            </tr>
          </table>
          <div class="funcprototype-spacer"> </div>
        </div>
      </div>
      <div class="refsect1" id="parameters">
        <h2>Parameters</h2>
        <div class="variablelist">
          <dl class="variablelist">
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>sampler</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>
                    Specifies the sampler to which the texture from which texels will be retrieved is bound.
                </p>
            </dd>
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>P</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>
                    Specifies the texture coordinates at which texture will be sampled.
                </p>
            </dd>
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>dPdx</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>
                    Specifies the partial derivative of <em class="parameter"><code>P</code></em> with respect to window x.
                </p>
            </dd>
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>dPdy</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>
                    Specifies the partial derivative of <em class="parameter"><code>P</code></em> with respect to window y.
                </p>
            </dd>
          </dl>
        </div>
      </div>
      <div class="refsect1" id="description">
        <h2>Description</h2>
        <p>
            <code class="function">textureGrad</code> performs a texture lookup at coordinate <em class="parameter"><code>P</code></em> from the
            texture bound to <em class="parameter"><code>sampler</code></em> with explicit texture coordinate gradiends as specified in
            <em class="parameter"><code>dPdx</code></em> and <em class="parameter"><code>dPdy</code></em>. Set:
        </p>
        <p>
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                <mml:mfrac>
                  <mml:mi>δs</mml:mi>
                  <mml:mi>δx</mml:mi>
                </mml:mfrac>
                <mml:mo>=</mml:mo>
                <mml:mfrac>
                  <mml:mi>δP.s</mml:mi>
                  <mml:mi>δx</mml:mi>
                </mml:mfrac>
            </mml:math>
        </p>
        <p>
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                <mml:mfrac>
                  <mml:mi>δs</mml:mi>
                  <mml:mi>δy</mml:mi>
                </mml:mfrac>
                <mml:mo>=</mml:mo>
                <mml:mfrac>
                  <mml:mi>δP.s</mml:mi>
                  <mml:mi>δy</mml:mi>
                </mml:mfrac>
            </mml:math>
        </p>
        <p>
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                <mml:mfrac>
                  <mml:mi>δt</mml:mi>
                  <mml:mi>δx</mml:mi>
                </mml:mfrac>
                <mml:mo>=</mml:mo>
                <mml:mfrac>
                  <mml:mi>δP.t</mml:mi>
                  <mml:mi>δx</mml:mi>
                </mml:mfrac>
            </mml:math>
        </p>
        <p>
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                <mml:mfrac>
                  <mml:mi>δt</mml:mi>
                  <mml:mi>δy</mml:mi>
                </mml:mfrac>
                <mml:mo>=</mml:mo>
                <mml:mfrac>
                  <mml:mi>δP.t</mml:mi>
                  <mml:mi>δy</mml:mi>
                </mml:mfrac>
            </mml:math>
        </p>
        <p>
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                <mml:mfrac>
                  <mml:mi>δr</mml:mi>
                  <mml:mi>δx</mml:mi>
                </mml:mfrac>
                <mml:mo>=</mml:mo>
                <mml:mn>0.0</mml:mn>
                <mml:mi>  for a 2D texture,  </mml:mi>
                <mml:mfrac>
                  <mml:mi>δP.p</mml:mi>
                  <mml:mi>δx</mml:mi>
                </mml:mfrac>
                <mml:mi>  otherwise</mml:mi>
            </mml:math>
        </p>
        <p>
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                <mml:mfrac>
                  <mml:mi>δr</mml:mi>
                  <mml:mi>δy</mml:mi>
                </mml:mfrac>
                <mml:mo>=</mml:mo>
                <mml:mn>0.0</mml:mn>
                <mml:mi>  for a 2D texture,  </mml:mi>
                <mml:mfrac>
                  <mml:mi>δP.p</mml:mi>
                  <mml:mi>δy</mml:mi>
                </mml:mfrac>
                <mml:mi>  otherwise</mml:mi>
            </mml:math>
        </p>
        <p>
            For the cube version, the partial derivatives of <em class="parameter"><code>P</code></em> are assumed to be
            in the coordinate system used before texture coordinates are projected onto the appropriate
            cube face.
        </p>
      </div>
      <div class="refsect1" id="versions">
        <h2>Version Support</h2>
        <div class="informaltable">
          <table style="border-collapse: collapse; border-top: 2px solid ; border-bottom: 2px solid ; border-left: 2px solid ; border-right: 2px solid ; ">
            <colgroup>
              <col style="text-align: left; "/>
              <col style="text-align: center; " class="firstvers"/>
              <col style="text-align: center; "/>
              <col style="text-align: center; " class="lastvers"/>
            </colgroup>
            <thead>
              <tr>
                <th style="text-align: left; border-right: 2px solid ; ">
                 
            </th>
                <th style="text-align: center; border-bottom: 2px solid ; " colspan="3">
                <span class="bold"><strong>OpenGL ES Shading Language Version</strong></span>
            </th>
              </tr>
              <tr>
                <th style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>Function Name</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>1.00</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.00</strong></span>
            </th>
                <th style="text-align: center; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.10</strong></span>
            </th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; ">textureGrad</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">✔</td>
                <td style="text-align: center; ">✔</td>
              </tr>
            </tbody>
          </table>
        </div>
      </div>
      <div class="refsect1" id="seealso">
        <h2>See Also</h2>
        <p>
            <a class="citerefentry" href="texelFetch.xhtml"><span class="citerefentry"><span class="refentrytitle">texelFetch</span></span></a>,
            <a class="citerefentry" href="texelFetchOffset.xhtml"><span class="citerefentry"><span class="refentrytitle">texelFetchOffset</span></span></a>,
            <a class="citerefentry" href="texture.xhtml"><span class="citerefentry"><span class="refentrytitle">texture</span></span></a>,
            <a class="citerefentry" href="textureGradOffset.xhtml"><span class="citerefentry"><span class="refentrytitle">textureGradOffset</span></span></a>,
            <a class="citerefentry" href="textureLod.xhtml"><span class="citerefentry"><span class="refentrytitle">textureLod</span></span></a>,
            <a class="citerefentry" href="textureLodOffset.xhtml"><span class="citerefentry"><span class="refentrytitle">textureLodOffset</span></span></a>,
            <a class="citerefentry" href="textureOffset.xhtml"><span class="citerefentry"><span class="refentrytitle">textureOffset</span></span></a>,
            <a class="citerefentry" href="textureProj.xhtml"><span class="citerefentry"><span class="refentrytitle">textureProj</span></span></a>,
            <a class="citerefentry" href="textureProjGrad.xhtml"><span class="citerefentry"><span class="refentrytitle">textureProjGrad</span></span></a>,
            <a class="citerefentry" href="textureProjGradOffset.xhtml"><span class="citerefentry"><span class="refentrytitle">textureProjGradOffset</span></span></a>,
            <a class="citerefentry" href="textureProjLod.xhtml"><span class="citerefentry"><span class="refentrytitle">textureProjLod</span></span></a>,
            <a class="citerefentry" href="textureProjLodOffset.xhtml"><span class="citerefentry"><span class="refentrytitle">textureProjLodOffset</span></span></a>,
            <a class="citerefentry" href="textureProjOffset.xhtml"><span class="citerefentry"><span class="refentrytitle">textureProjOffset</span></span></a>,
            <a class="citerefentry" href="textureSize.xhtml"><span class="citerefentry"><span class="refentrytitle">textureSize</span></span></a>
        </p>
      </div>
      <div class="refsect1" id="Copyright">
        <h2>Copyright</h2>
        <p>
            Copyright <span class="trademark"/>© 2011-2014 Khronos Group.
            This material may be distributed subject to the terms and conditions set forth in
            the Open Publication License, v 1.0, 8 June 1999.
            <a class="link" href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>.
        </p>
      </div>
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